1. Field of the Invention
This device relates to an augmented turbine power plant that extracts energy from a moving stream such as a river, an ocean current, and the wind.
2. Description of Prior Art
Wind, ocean currents, and rivers have long been recognized as sources of alternate energy. Two groups of devices lead the state of the art for converting moving stream energy to useful electrical or mechanical energy.
The more recent and current leader in the state of the art in wind energy conversion is the twin blade device. It consists of specifically shaped propellar blades pivoted at the top of a support structure. The shape of the blades cause a circulation in the air stream around the blades which produces rotation. However these blades work efficiently at only high tip speeds. These devices are impractical for underwater use and sites with lower average wind velocities.
The larger the blades become, the lower the rotations per minute and requires less efficient high gearing ratios to a generator.
The augmentation of a sawmill waterwheel by constructing a dam across a stream is the oldest representative of the second group of devices. The modern versions are hydroelectric dams. However dams are impractical in wind and ocean currents. Dams require massive investment, are only feasible at a few sites, and cause considerable damage to the environment. Several recent attempts have been made to augment a turbine to eliminate the inadequacies of the current leaders in the state of the art. Murphy's "Wind Motor Machine" demonstrates many of the problems with augmenting a turbine in a free stream. A converging tube augmenter focuses more of the wind than would effect the turbine without the tube. However the tube requires considerable structural support to obtain large volumes of wind and must be rolled around tracks at ground level. This places the mouth of the tube in the slowest velocity stream present at a site due to ground drag effects. Uzzell's "Method and Apparatus for Generating Power From Wind Currents" elevates a Venturi tube type augmenter above ground drag effects, however the support structure required to elevate the augmenter makes it uneconomical for large volumes of wind required in a slow moving stream. McFarland's "Wind Power Generator" uses a shield to improve efficiency of a verticle axis turbine. However the structural requirements of the shield and turbines and the ground drag effects on the turbine results in similar shortcomings as Murphy's device. Hope's "Wind Operated Power Plant" uses an airplane wing type augmenter and a vertical construction efficiency. However the turbines interfere with the circulation required by the wing augmenters to perform their function. Other patents referenced are less promising than those devices discused above.